Short-distance data sharing between users, small-scale social and commercial activities and a specific service oriented to a local specific user all gradually become nonnegligible growth points in a next-stage wireless platform. For such a service type with an obvious local characteristic, under a normal condition, service data source of the type service is not required to pass through a core network, and a service is merely required to be implemented between users. Such a communication mode has a characteristic obviously different from a conventional cellular system communication mode, and for a short-distance communication user capable of using a D2D communication manner, D2D transmission not only saves radio spectrum resources, but also reduces data transmission pressure of a core network, and may reduce occupied system resources, improve spectral efficiency of a cellular communication system, reduce transmitted power consumption of User Equipment (UE) and reduce network operation cost to a great extent.
Resource allocation of D2D UE is divided into two working modes from a sending layer according to whether the D2D UE is covered by a related network or not: Mode 1: an eNodeB or a rel-10 relay node schedules a resource for sending of the D2D UE; and Mode 2: the D2D UE selects a resource in a resource pool for sending of the D2D UE by itself.
No matter which manner is adopted, since direct communication is adopted between UE during D2D communication, Transmitting (Tx) UE is required to send Scheduling Assignment (SA) information configured to indicate physical channel resource information and control information of sent D2D data. A difference between Mode 1 and Mode 2 is that an eNodeB configures SA and data resources for the Tx UE in Mode 1 while the Tx UE selects the SA and data resources from a resource pool in Mode 2. In each scenario, it is necessary to schedule the SA resource at first, SA indicates the data resource, and as a data indication carrier, the SA is equivalent to control information of data, and is required to be highly reliable. At present, SA pattern designing just emerges in a standard, and such a conflict problem in Mode 2 is that system duplexity restricts to mutual monitoring. Therefore, it is very important to improve SA designing reliability. At present, a retransmission support mechanism has been proposed in a conference to further improve SA reliability.
A D2D resource pool is a group of time-frequency resources configured for D2D. UE, and may be pre-configured or configured by a network. The D2D resource pool includes an SA resource pool and a data resource pool, and a Time Division Multiplex (TDM) configuration is adopted. FIG. 1 is a schematic diagram of resource indication and a relationship between an SA field and a data field according to a related technology. As shown in FIG. 1, SA includes indexes and frequency-domain offsets, resources for data are indicated by T-PRTs and frequency domain in the SA, and each SA index includes certain time-frequency resources in Resource Units (RUs), such as 1˜2 Physical Resource Blocks (PRBs) on the frequency domain and a sub-frame on a time domain. In Mode 1, a scheduling eNodeB schedules a resource configuration of SA and data of Tx UE, the eNodeB notifies the UE, the Tx UE sends the SA and the data, and receiving UE reads the SA to obtain a resource indication and control information of the data, and then reads data information; and in Mode 2, the Tx UE selects an SA resource and a data resource randomly or in a certain manner, and indicates resource and control information of the data through the SA, and the receiving UE reads the SA to obtain the resource indication and control information of the data, and then reads the data information. But in the two modes, mutual monitoring of the UE may be restricted by duplexity.
Therefore, there exists the problem of incapability of UE in a D2D half-duplex system in monitoring each other in the related technology.